Purpose: High intensity training has been shown to produce more profound effects on cardiovascular function and aerobic capacity than iso-caloric low and moderate intensity training. The aim of the present study was to explore metabolic and mechano-energetic changes in the heart following endurance exercise training of both high and moderate intensity.

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Conclusions: This study shows that high intensity training is required for induction of changes in cardiac substrate utilization and energetics, which may contribute to the superior effects of high compared with moderate intensity training in terms of increasing aerobic capacity.